<?php
$prize_arr = array(   
 '0' => array('id'=>1,'prize'=>'平板电脑','v'=>3),   
 '1' => array('id'=>2,'prize'=>'数码相机','v'=>5),   
 '2' => array('id'=>3,'prize'=>'音箱设备','v'=>10),   
 '3' => array('id'=>4,'prize'=>'4G优盘','v'=>12),   
 '4' => array('id'=>5,'prize'=>'Q币10元','v'=>20),   
 '5' => array('id'=>6,'prize'=>'下次没准就能中哦','v'=>50),   
);   
foreach ($prize_arr as $key => $val) {   
 	$arr[$val['id']] = $val['v'];   
}   
$rid = getRand($arr); // 根据概率获取奖项id   
$res['msg'] = ($rid==6)?0:1; // 如果为0则没中   
$res['prize'] = $prize_arr[$rid-1]['prize']; // 中奖项   
echo json_encode($res);   
// 计算概率   
function getRand($proArr) {   
 	$result = '';   
 	//概率数组的总概率精度   
 	$proSum = array_sum($proArr);   
 	//概率数组循环   
 	foreach ($proArr as $key => $proCur) {   
 		$randNum = mt_rand(1, $proSum);   
 		if ($randNum <= $proCur) {   
 			$result = $key;   
 			break;   
	 	} else {   
	 		$proSum -= $proCur;   
	 	}   
 	}   
 	unset ($proArr);   
 	return $result;   
}


